fpeel: i'm not sure what you mean when you say you "put the tv and cable box in the loop," tho i assume you aren't plugging any cable leads into your sf l-1 (don't think it can be done, can it?). in any event, i agree with jeff that the most plausible problem is with the cable ground. i have my digital cable grounded into a copper rod well away from my electrical boxes; there are no common connections at all. i, likewise, have my telephone lines junction box and all associated wiring segregated from my electrical and coax. i have found an inexplicable reduction in what i assume was rf in my audio system when i recently replaced the cable box to tv coax with composite connections. i'm told that s video works even better but my cable box won't accept such outputs. i think you're on the right track. do check all splitters, too, and eliminate as many as you can. this will also enhance your video output. best of luck. -kelly